* {
    padding: 0;
    margin: 0;
    list-style: none;
}

.header {
    border: 1px solid black;
    height: 100px;
    /* 弹性布局 flex */
    display: flex;
    justify-content: space-evenly;
    align-items: center;
    min-width: 1000px;
}

.header .logo {
    border: 1px solid black;
    width: 100px;
    height: 100px;
    margin-top: 20px;
    display: inline-block;
}

.header .nav {
    border: 1px solid black;
    height: 50px;
    /* 弹性布局flex */
    display: flex;
    /* 水平方向排列方式 */
    justify-content: space-evenly;
    /* 垂直方向排列方式 */
    align-items: center;
}

.header .nav ul {
    /* 弹性布局 flex */
    display: flex;
}

.header .nav ul li {
    /* 使li标签为行内块级元素 */
    display: inline-block;
    width: 100px;
    border: 1px solid black;
    height: 20px;
}

.header .search {
    width: 100px;
    height: 50px;
    border: 1px solid black;
}

.header .icon {
    width: 100px;
    height: 50px;
    border: 1px solid black;
    /* 相对定位 */
    position: relative;
    padding-left: 30px;
    /* 怪异盒模型（内减盒模型） */
    box-sizing: border-box;
}

.header .icon .icon_top {
    width: 50px;
    height: 50px;
    border: 1px solid black;
    /* 相对 icon定位 */
    position: absolute;
    /* z-index */
    z-index: 10;
}

.header .icon .icon_in {
    width: 50px;
    height: 50px;
    border: 1px solid black;
    background-color: blue;
    /* 相对 icon定位 */
    position: absolute;
    /* z-index */
    z-index: 1;
}

.header .login {
    width: 100px;
    height: 50px;
    border: 1px solid black;
}